Biomarkers of exposure to metals and metalloids have proven to be powerful tools for epidemiologic studies[unreadable] that seek to study associations between exposures and human health effects. The Trace Metals Core Lab[unreadable] came into existence in 1994 as part of our NIEHS Center, and received a rating of outstanding at NIEHS[unreadable] Center site visits that occurred in 1997 and 2002.[unreadable] The Laboratory participates in multiple quality control programs and has an outstanding record of past[unreadable] performance. Biomedical research Projects #2, #3 and #4, which take place in Bangladesh and New[unreadable] Hampshire, propose to test a set of novel hypotheses concerning the mechanisms and effects of exposure to[unreadable] As and Mn from drinking water. These projects collectively require the analysis of more than 60,000[unreadable] biological specimens; this estimate approximates the total of 70,000 specimens that have been successfully[unreadable] measured during the past five years.[unreadable] The biological specimens to be analyzed and stored in the Trace Metals Core Lab include blood, urine and[unreadable] toenails. The methodologies employed will include graphite furnace atomic absorption spectrophotometry[unreadable] (GFAAS) (e.g., arsenic in urine and lead in blood), inductively-coupled plasma mass spectrometry with[unreadable] dynamic reaction cell (ICP-MS-DRC) (e.g., total As, Mn and Se in blood), HPLC coupled to ICP-MS-DRC[unreadable] (e.g., arsenic metabolites in urine and blood), and ELISA technology (clara cell protein-16). The Trace[unreadable] Metals Core Laboratory is well equipped to carry out these and other requested analyses at no cost to[unreadable] members of this Superfund Basic Research Program.